JPH11235062A - Vibration actuator driver and lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a mounting space, make assembly easy and, further, reduce the cost. SOLUTION: Vibrators 11 which are made to vibrate by a driving signal, an annular relative movement member 3 which is relatively moved by the contact with the vibrators 11, and a pressurizing support member 2 which supports the vibrators 11 and brings them into pressure contact with the relative motion member 3, are provided. The pressurizing support member 2 has an annular base part 2a, flat spring parts 2b which are supported on the base part 2a so as to form cantilevers and support pin 2c parts provided on the free end sides of the flat springs 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator driving device which makes a relative motion with a ring-shaped member by pressurizing contact with a vibrator, and a lens for driving a photographing optical system using such a vibration actuator driving device. It relates to a lens barrel.

[0002]

2. Description of the Related Art Conventionally, this type of vibration actuator has
An elastic body is vibrated by an electromechanical transducer (a piezoelectric element, an electrostrictive element, or the like, hereinafter, generally referred to as a piezoelectric element), and a plurality of vibration modes are generated harmoniously, thereby causing an elliptical motion on the surface of the elastic body. Is caused to cause the elastic body to run on its own or to drive a moving body that comes into contact with the elastic body.

Specifically, an ultrasonic motor has been developed which obtains a driving force by applying an AC voltage to a piezoelectric element bonded to an elastic body to generate a longitudinal vibration and a bending vibration in the elastic body harmoniously. "Piezoelectric linear motor for optical pickup movement" (Yoshio Tomikawa et al .: Proceedings of the 5th Dynamic Symposium on Electromagnetic Force pp393
398) describe the configuration and load characteristics. In addition, a self-propelled device is shown in a new edition ultrasonic motor (Sadayuki Ueba, Yoshiro Tomikawa, pp145-146, published by Trikeps).

This ultrasonic motor has a flat plate shape, and is designed to have a resonance frequency of a first-order longitudinal vibration and a fourth-order (or eighth-order) bending vibration at very close values. Then, by applying an AC voltage having a frequency close to the two resonance frequencies to the piezoelectric element in two phases (phase difference: 90 °), the elastic body generates vibration in which the two modes are in harmony. This elastic body is provided with a projection at a portion that becomes an antinode of the bending vibration, and a driving force is obtained by an elliptical movement of the tip of the projection. Further, by setting the phase difference between the two phases of the AC voltage to 90 ° and −90 °, the driving direction is reversed.

The resonance frequency of the first-order longitudinal vibration and the fourth-order bending vibration of a flat plate is expressed by the following equation.

[0006]

(Equation 1)

[0007]

However, the conventional vibration actuator driving device has a problem that a relatively large space is required at the time of mounting since the vibrator is pressed by a coil spring. In addition, since the vibrator is pressurized and supported by another member, there is a problem that the assemblability is poor and the parts cost is relatively high.

An object of the present invention is to reduce the mounting space,
An object of the present invention is to provide a vibration actuator driving device which is easy to assemble and can reduce the cost, and a lens barrel using such a vibration actuator driving device.

[0009]

According to a first aspect of the present invention, there is provided a vibrator that vibrates in response to a drive signal, and a ring-shaped relative motion that performs relative motion by contacting the vibrator. A member and a pressure support member that supports the vibrator and presses the relative motion member into pressure contact, the pressure support member being a cantilever supported by the ring-shaped base portion and the base portion. A vibration actuator driving device comprising: a leaf spring portion; and a support portion provided on a free end side of the leaf spring portion.

According to a second aspect of the present invention, in the vibration actuator driving device according to the first aspect, the leaf spring portion includes:
Provided is a vibration actuator driving device that is provided on the base portion and that can press the plurality of vibrators.

According to a third aspect of the present invention, in the vibration actuator driving device according to the first aspect, the leaf spring portion includes:
A vibration actuator drive is provided, the free end of which is oriented in the circumferential direction of the relative motion member.

According to a fourth aspect of the present invention, in the vibration actuator driving device according to the first aspect, the plate spring portion includes:
A vibration actuator drive is provided, the free end of which is oriented radially of the relative motion member.

According to a fifth aspect of the present invention, in the vibration actuator driving device according to the fourth aspect, the plate spring portion is
Provided is a vibration actuator driving device capable of adjusting the pressing force in the radial direction.

According to the invention of claim 6, the vibrator oscillated by the drive signal, a ring-shaped relative motion member that makes relative motion by contacting the vibrator, and the vibrator and the relative motion member are added. A supporting member that supports the vibrator; a first supporting portion that supports the vibrator from an upper surface; and a second support that supports the vibrator from a side surface. A vibration actuator drive device comprising:

According to a seventh aspect of the present invention, in the vibration actuator driving device according to the sixth aspect, the second support portion supports the vibrator at a position of a node of vibration generated in the vibrator. A drive is provided.

According to an eighth aspect of the present invention, in the vibration actuator driving device according to any one of the first to seventh aspects, the vibrator generates bending vibration and longitudinal vibration harmoniously. And a vibration actuator driving device for generating a driving force.

According to a ninth aspect of the present invention, there is provided an optical system supporting portion that supports at least a part of a photographing optical system and is movable in a direction of an optical axis of the photographing optical system. 2. The vibration actuator drive device according to claim 1, further comprising: a conversion unit configured to convert the rotational motion about the optical axis into a linear motion in the optical axis direction and transmit the linear motion to the optical system support unit. Constitutes a rotating part in which the relative motion member is rotatable around the optical axis, and the vibrator rotationally drives the rotating part by frictionally contacting a part of the rotating part, or The rotating unit is provided in the rotating unit, and rotationally drives the rotating unit by being in frictional contact with a part of another member facing the rotating unit, and the converting unit rotates the rotating unit in the optical axis direction. Lens barrel that converts it into linear motion Subjected to.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The present invention will be described in more detail by way of embodiments. (First Embodiment) FIGS. 1 to 3 show a first embodiment of a vibration actuator driving device according to the present invention.
FIG. 1 is a perspective view showing the entire driving device, FIG. 2 is an exploded perspective view showing FIG. 1 disassembled for each part, and FIG. 3 is a perspective view showing the pressure supporting member of FIG. FIG. 1 shows a state in which some parts are omitted for easy understanding. In the following embodiments, an example will be described in which the vibration actuator is an ultrasonic motor that vibrates in an ultrasonic region.

The driving device according to the first embodiment includes a base member 1
, A pressure support member 2, a relative motion member 3, a bearing 4, three vibration actuators 10, and the like. The base member 1 is a member for mounting the vibration actuator 10, and as shown in FIG.
It has a ring portion 1a, a second ring portion 1b having a medium diameter, and a flange portion 1c having a small diameter. Three vibration actuators 1
0 are arranged at substantially equal intervals with respect to the base member 1 as shown in FIG.

The pressure supporting member 2 is a member that supports each vibration actuator 10 and presses the vibration actuator 10 against the relative movement member 3. As shown in FIG. 3, the pressure supporting member 2 has a ring-shaped base portion 2a attached to the first ring portion 1a of the base member 1 and a part of the base portion 3a having a rectangular shape at three positions. A leaf spring portion 2b having a spring portion 2b-1 which is formed by being bent and raised obliquely to form a cantilevered spring, and a flat mounting portion 2b-2 connected to the spring portion 2b-1; And two support pins 2c and 2c 'provided on the mounting portion 2b-2 of the leaf spring portion 2b.

The relative motion member 3 is a member that makes contact with each of the vibration actuators 10 and performs relative motion with the vibration actuators 10, and is a ring-shaped driven member here.

The bearing 4 is a member for rotatably attaching the relative motion member 3 to the base member 1. The bearing 4 is inserted into the second ring portion 1b of the base member 1, and supports the relative motion member 3 on its outer periphery. I have.

The vibration actuator 10 comes into contact with the relative motion member 3 while being pressed by the pressure support member 2,
Generates driving force. In addition, the vibration actuator 10
It is supported in a state where it is positioned by the support pins 2c and 2c 'of the pressure support member 2.

Next, the structure of the vibration actuator 10
The principle of driving the relative motion member 3 will be described. FIG. 4 is a perspective view illustrating a vibration actuator of the driving device according to the first embodiment, and FIG. 5 is a block diagram illustrating a driving circuit of the vibration actuator. The vibration actuator 10 includes an elastic body 11 having a rectangular flat plate shape and six piezoelectric elements 12a, 12a ', 12b, 12b', 12p,
12p '.

The elastic body 11 is formed with driving force take-out portions 11a and 11b on the protrusions. The drive force take-out portions 11a and 11b come into pressure contact with the relative motion member 3 so that the driving force is relatively moved. Transmit to member 3. The driving force extracting portions 11 a and 11 b are provided at positions that are antinodes of bending vibration generated in the elastic body 11. The driving force extracting portions 11a and 11b may be formed integrally with the main body of the elastic body 11, or may be formed by bonding a sliding material made of a resin having abrasion resistance.

The piezoelectric elements 12a, 12a ', 12b, 12
b ′ is a driving piezoelectric element, and the piezoelectric elements 12a and 12a
a ′, a first AC voltage is applied to the piezoelectric elements 12 b and 12
By applying a second AC voltage having a phase different from that of the first AC voltage to b ′, by their piezoelectric effect,
The first-order longitudinal vibration and the fourth-order bending vibration are generated harmoniously in the elastic body 11. Due to these vibrations, the driving force take-out unit 1
Elliptical motion occurs in 1a and 11b, and relative motion occurs between the elastic body 11 and the relative motion member 3. The piezoelectric elements 12p and 12p 'are piezoelectric elements for monitoring a state of vibration generated in the elastic body 11, and are connected to a control circuit 21 described later. The elastic body 11 has a main body of GND.
Connected to potential.

As shown in FIG. 5, the drive circuit 20 includes a control circuit 21, an oscillator 22, a phase shifter 23, an amplifier 2
4, 25, and the like.

The control circuit 21 includes the piezoelectric elements 12p and 12p.
A circuit that generates a control signal based on the output of p ′, and the output of which is connected to the oscillator 22. The oscillator 22 oscillates a high-frequency AC voltage based on a control signal from the control circuit 21. The output of the oscillator 22 is branched, and one of the outputs is shifted by 90 ° by the phase shifter 23. Via an amplifier 24, as a first AC voltage,
It is connected to the piezoelectric elements 12a and 12a '. The other side is connected to the piezoelectric elements 12b and 12b 'as a second AC voltage via the amplifier 25.
The phase shifter 23 adjusts the phase of the AC voltage from the oscillator 22 by 90
° (or -90 °).

The vibration actuator 10 includes a driving circuit 20
, The first AC voltage is applied to the piezoelectric elements 12a and 12a ', and the second AC voltage is applied to the piezoelectric elements 12b and 12b'. The first and second AC voltages have an electrical phase of 9
When the two-phase AC voltage is applied, the driving force extracting portions 11a, 11
Elliptic motion occurs at the tip of b. In the vibration actuator drive device of the first embodiment, a drive circuit 20 is provided for each of the three vibration actuators 10. Then, by generating a driving force in the same direction on all the vibration actuators 10, the relative motion member 3 is driven to rotate around the rotation axis shown in FIG.

According to the first embodiment described above, since the pressure supporting member in which the supporting pin is combined with the leaf spring portion is used, a space for mounting is small. Also,
Since the pressurization and support are performed with an integrated member,
The assemblability is good, and the cost of parts can be reduced.

Further, since the leaf spring portions 2b are provided at three places of the base portion 2a, the three vibration actuators 10 can be independently supported by pressure with respect to the relative moving member 3, and the floating and tilting can be performed. Does not occur. In contrast to the conventional annular ultrasonic motor which requires strict flatness of the stator (elastic body) and the rotor (relative moving member), in the present embodiment, the relative moving member 3 and the vibration actuator 10 There is an advantage that the processing cost can be reduced because only the flatness of the driving force extracting portions 11a and 11b is required.

(Second Embodiment) FIG. 6 is a schematic view showing a pressure supporting member of a vibration actuator driving device according to a second embodiment. In each of the embodiments described below, portions that perform the same functions as in the first embodiment described above are denoted by the same reference numerals, and redundant description will be omitted as appropriate. In the first embodiment, the bending direction of the leaf spring portion 2b is the circumferential direction. However, in the pressing support member 2B of the second embodiment, the leaf spring portion 2d is different in that the bending direction is the radial direction. I do.

The leaf spring 2d is provided separately from the base 2a. The leaf spring 2d is
d-1 and the mounting part 2 connected to the distal end side of the spring part 2d-1
d-2 and the base 2 connected to the root side of the spring 2d-1
d-3, a mounting member 2d-4 such as a screw for mounting the base 2d-3 to the base 2a, a holding portion 2d-5 formed on the mounting portion 2d-2, and the like.

The leaf spring portion 2d can be applied to the vibration actuator 10 in the width direction by deforming the mounting portion 2d-2 in the direction of arrow B as shown by the two-dot chain line in FIG. The pressure can be adjusted. Therefore, the speed difference between the inner peripheral side and the outer peripheral side of the relative speed (peripheral speed) between the vibration actuator 10 and the relative motion member 3 can be suppressed by adjusting the pressing force. That is, if the force applied to the outer peripheral side having a higher peripheral speed is made larger than the inner peripheral side, the driving force transmitted at the outer peripheral side becomes larger than that at the inner peripheral side, and the speed difference is eliminated. In the second embodiment, since the bending direction of the leaf spring portion 2d is the radial direction, the relative movement member 3
Irrespective of which direction is rotated, the pressing force acting between the vibration actuator 10 and the relative motion member 3 can be maintained at a constant value.

(Third Embodiment) FIG. 7 is a view showing a third embodiment of the vibration actuator driving device according to the present invention. In the third embodiment, the vibration actuator 10C
A hole 11c (not a through hole) is formed substantially at the center of the elastic body 11, and the support pin 2g of the pressure support member 2C is fitted into the hole 11c. If necessary, a through hole may be provided in the piezoelectric element 12.

The pressure supporting member 2C is provided on the base portion 2e having the wall portion 2e-1, the leaf spring portion 2f, one support pin 2g, and the wall portion 2e-1. There are provided two holding pins 2h for holding the side surface. The holding pin 2h is provided in order to prevent the elastic body 11 from rotating because the elastic body 11 rotates only with the support pin 2g. It is preferable that the holding pin 2h makes contact at the position of the node of the bending vibration generated in the elastic body 11.

The pressure supporting member 2C is connected to the GND potential, and also has a role to set the elastic body 11 to the GND potential.

Further, as shown in FIG.
Instead of h, the holding member 2i may have a width in the height direction and a wedge-shaped tip. Here, the holding pin 2h or the holding member 2i is
, And is not necessarily fitted into the elastic body 11.

(Embodiment of Lens Barrel) FIG. 8 is a sectional view showing an embodiment of a lens barrel according to the present invention, and FIG. 9 is a diagram showing a vibration actuator driving device for a lens barrel according to this embodiment. It is the figure extracted and shown.

The frame 36 is a member for holding the focusing lens group L1. The frame 36 is connected to the fixed cylinder 31 by a helicoid 39. A rotating cylinder 32 is rotatably mounted in front of the fixed cylinder 31 on the optical axis. A key groove 32a is formed on the inner periphery of the rotary cylinder 32 in parallel with the optical axis. Further, the frame 36 of the focusing lens unit L1
Is formed with a key 36a, and the key 36a is engaged with the key groove 32a.

A rotor 3D is integrally fixed to the end of the rotary cylinder 32 behind the optical axis. The rotor 3D has a flat portion 3D-1 perpendicular to the optical axis at the rear of the optical axis. Also,
The rotor 3D has a circumferential groove 3D-2 on the outer peripheral surface. Circumferential groove 3
The ball 4D is spread on D-2. The sphere 4D is
This is a member that brings the rotor 3D into rolling contact with the fixed cylinder 31 to ensure smooth rotation of the rotor 3D. Sphere 4D
A holding ring 34 is screwed into the inner peripheral side of the fixed cylinder 31 in front of the optical axis. The holding ring 34 is a member that limits the movement of the ball 4D in the optical axis direction. Due to the action of the retaining ring 34, the ball 4D does not jump out of the lens barrel after the lens barrel is assembled. In addition, the retaining ring 34 also restricts the movement of the rotor 3D in the optical axis direction together with the ball 4D. Therefore, the distance between the rotor 3D and the vibration actuator 10 increases, and the transmission efficiency of the driving force to the rotor 3D does not decrease.

A vibration actuator 10 is disposed behind the optical axis of the rotor 3D so as to face the flat portion 3D-1. As shown in FIG. 9, three vibration actuators 10 are arranged at substantially equal intervals. The vibration actuator 10 is the same as that shown in FIG. 4, and the pressure support member 2 is the same as that shown in FIGS.
The elastic body 11 is pressed in the direction of the flat part 3D-1 of the rotor 3D.

The frame 37 is a member for holding the focal length adjusting lens unit L2. The frame body 37 has through-holes 37a and 37b (not shown because 37b overlaps with 37a) parallel to the optical axis direction in a thick portion, and a flat portion 37c is formed in a part of the outer periphery. ing. Through hole 37a (37
In (b), a linear guide 38 is inserted. The linear guide 38 is disposed parallel to the optical axis, and
1 and 33 are fixed.

A linear vibration actuator 40 is arranged at a position facing the flat portion 37c of the frame 37. The vibration actuator 40 mainly includes a vibrator 41
And a pressure member 42. Here, body 4
1 is substantially the same as the elastic body 11 of the vibration actuator 10.

As described above, in the present embodiment, a rotational driving force is applied to the rotor 3D using the vibration actuator 10. Further, the rotational motion of the rotor 3D is converted into a linear motion in the optical axis direction by the helicoid 39, and then used for driving the focus adjustment lens group L1. Therefore, in the present embodiment, the positioning accuracy of the focusing lens unit L1 in the optical axis direction is mainly determined by the characteristics of the helicoid 39. In other words, in the present embodiment, regardless of the size of the drive unit of the vibration actuator 10, the shape of the helicoid 39 is appropriately determined so that the focusing lens group L1
It is possible to improve the positioning accuracy of the camera and perform highly accurate focusing adjustment.

Further, the vibration actuator 10 is
Since the flat portion 3D-1 contacts only a part of D, there is an advantage that the flat portion 3D-1 does not require very strict flatness. Generally, in a vibration actuator such as an ultrasonic motor, the amplitude of the vibration generated in the vibrator is on the order of microns.
Flatness is required for a moving member (rotor) that comes into frictional contact with a vibrator and moves relatively. In addition, the requirement for flatness increases with the increase in the contact area between the vibrator and the moving element. Therefore, provisionally, Japanese Patent Application Laid-Open No.
In the case where a ring-shaped ultrasonic motor is employed as in the lens barrel disclosed in No. 17, the ultrasonic motor and the rotor are in contact with each other over the entire circumference of the rotor. The requirements become very strict. On the other hand, in this embodiment, a linear vibration actuator is adopted,
Since this is brought into contact with only a part of the rotor 3D, it is sufficient that the flatness of the rotor is guaranteed within a relatively narrow area corresponding to the length of the vibration actuator 10. Therefore, as described above, the flatness requirement of the flat portion 3D-1 of the rotor 3D is relatively moderate, and the manufacture thereof is easy.

Further, there is an advantage that the pressing force to be applied to the vibration actuator is smaller than in the case where a ring type ultrasonic motor is employed. This is because the force to be applied to the linear vibration actuator having a small contact area with the rotor is naturally smaller when the pressing force per unit area is the same. Therefore, in the present embodiment, it is not necessary to make the structure of the pressure support members of the vibration actuator and the surrounding members supporting these components as strong as in the case of using the annular ultrasonic motor.

(Modifications) Various modifications and changes are possible without being limited to the above-described embodiments, and they are also within the equivalent scope of the present invention. In each of the above embodiments, the ultrasonic motor using the first-order longitudinal vibration and the fourth-order bending vibration has been described. However, the present invention is similarly applied to a motor using the n-th longitudinal vibration and the m-th bending vibration. Can be applied to Further, the lens barrel can use the vibration actuator driving device of the second or third embodiment.

[0049]

As described above, according to the present invention, the mounting space can be reduced, the cost of parts can be reduced, and the assemblability can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an entire driving device of a vibration actuator driving device according to a first embodiment.

FIG. 2 is an exploded perspective view showing components of the vibration actuator driving device according to the first embodiment in an exploded manner.

FIG. 3 is a perspective view showing a pressure support member of the vibration actuator driving device according to the first embodiment.

FIG. 4 is a perspective view showing a vibration actuator of the driving device according to the first embodiment.

FIG. 5 is a block diagram illustrating a drive circuit of the drive device according to the first embodiment.

FIG. 6 is a schematic view illustrating a pressure supporting member in a vibration actuator driving device according to a second embodiment of the present invention. FIG. 6A is a cross-sectional view of the pressure supporting member cut along a plane substantially parallel to the rotation axis. FIG. 6B is a perspective view showing a part of the pressure supporting member.

FIG. 7 is a schematic diagram showing a configuration of a third embodiment of the vibration actuator driving device according to the present invention. FIG. 7 (a)
FIG. 3 is a perspective view illustrating a configuration of a vibration actuator. FIG.
(B) is a figure which shows the state which looked at the structure of the vibration actuator and the pressurization support member of its vicinity from the axial direction of the rotating shaft. FIG. 7C is a sectional view taken along the line BB in FIG. 7B. FIG. 7D is a sectional view taken along the line AA in FIG. 7B. FIG. 7E is a perspective view illustrating a part of a pressure supporting member according to a modification of the third embodiment.

FIG. 8 is a sectional view showing an embodiment of a lens barrel according to the present invention.

FIG. 9 is a diagram illustrating a part of the vibration actuator driving device for the lens barrel according to the present embodiment that is extracted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base member 2 Pressure support member 3 Relative motion member 4 Bearing 10 Vibration actuator 11 Elastic body 11a, 11b Driving force extraction part 12a, 12a ', 12b, 12b' Driving piezoelectric element

Claims (9)

[Claims] A vibrator that vibrates according to a drive signal; a ring-shaped relative motion member that makes relative motion by contacting with the vibrator; and supports the vibrator by pressure contact with the relative motion member. A pressure support member, wherein the pressure support member is provided on a ring-shaped base portion, a leaf spring portion cantilevered on the base portion, and a free end side of the leaf spring portion. A vibration actuator drive device comprising: a support portion. 2. The vibration actuator driving device according to claim 1, wherein a plurality of the leaf springs are provided on the base.
A vibration actuator driving device, wherein a plurality of the vibrators can be pressurized. 3. The vibration actuator driving device according to claim 1, wherein a free end of the leaf spring is oriented in a circumferential direction of the relative motion member. 4. The vibration actuator driving device according to claim 1, wherein the leaf spring portion has a free end directed in a radial direction of the relative motion member. 5. The vibration actuator driving device according to claim 4, wherein the leaf spring portion is capable of adjusting the pressing force in the radial direction. 6. A vibrator that vibrates according to a drive signal, a ring-shaped relative movement member that makes relative movement by contacting with the vibrator, and a pressing member that presses the vibrator and the relative movement member. A supporting member that supports the vibrator; the supporting member includes: a first supporting portion that supports the vibrator from an upper surface; and a second supporting portion that supports the vibrator from a side surface. A vibration actuator driving device characterized by the above-mentioned. 7. The vibration actuator according to claim 6, wherein the second support portion supports the vibrator at a position of a node of vibration generated in the vibrator. Drive. 8. The vibration actuator driving device according to claim 1, wherein the vibrator generates a driving force by generating bending vibration and longitudinal vibration in harmony. A vibration actuator drive device characterized by the above-mentioned. 9. Supporting at least a part of a photographing optical system,
An optical system supporting portion movable in a direction of an optical axis of the photographing optical system, a vibration actuator driving device according to any one of claims 1 to 8, and a rotational movement around the optical axis. A conversion unit that converts the motion into a linear motion in the direction of the optical axis and transmits the linear motion to the optical system support unit. The vibrator drives the rotating part by rotating it by frictional contact with a part of the rotating part, or the vibrator is provided on the rotating part and rubs against a part of another member facing the rotating part. The lens barrel, wherein the rotating unit is driven to rotate by contact, and the converting unit converts the rotating motion of the rotating unit into the linear motion in the optical axis direction.